The end-stage cardiac patients who cannot undergo heart transplantation owing to age limitation, lack of donor hearts or complications in using immunosuppressive drugs, are essentially salvaged by LAVD and TAH devices. An estimated 30,000 to 50,000 patients are currently aided by such devices annually in the U.S. alone. There is a need for a reliable power systems that could support the devices for longer hours without any interruption. A compact and lightweight system based on PEM fuel cell technology would be most suitable power source for the said applications capable of giving up to 16 hours of performance on a single fuel cartridge. To accomplish this, a Phase l program is proposed to demonstrate the feasibility of producing a 10 W fuel cell stack assembly weighing approximately 200 g. The following are the specific aims of the Phase l feasibility study: 1. To attain the highest possible performance (e.g., 0.7 V at 0.1 A/cm2 for the MEAs operated with ambient H2/air (natural convection air flow); to identify structural features of these MEAs and optimize their fabrication process; 2. To develop and evaluate unitized MEA-bipolar plates using appropriate support materials 3. To design, develop and construct a 10 W stack assembly, and demonstrate a performance level that meets the stated goals. PROPOSED COMMERCIAL APPLICATIONS: There are approximately 50,000 patients with the need for LVAD type devices. Assuming 20% of these patients will be on electrically powered systems, and each patient will use two power packs, there is an immediate market for 20,000 fuel cell power packs. The magnitude of this business is quite suitable to small manufacturing companies. Successful implementation of this concept will also open the market for other battery replacement applications. In the next five years, the market for such applications is projected to be approximately $50-70 million/year.